1. Field of the Invention
The present invention relates to a system for offering a color conversion profile capable of color conversion with high accuracy, said color conversion profile being used for printing.
2. Description of the Related Art
The image devices such as displays and printers usually employ the color image data which expresses in tone the color of each pixel in term of specific color components. For example, the image data specify colors by means of any of color spaces, such as RGB color space that uses three colors of R (red), G (green), and B (blue), and CMY color space that uses C (cyan), M (magenta), and Y (yellow), including lc (light cyan), lm (light magenta), DY (dark yellow), and K (black). These colors are usually device-dependent colors inherent in individual image devices. One way to permit various image devices to produce identical colors is by color conversion which is performed by means of a profile conforming to the ICC standard.
The ICC profile performs color conversion by using a profile which converts the colors of input image data into the colors of the device-independent color space, a profile which converts the colors of the device-independent color space into the colors of the output image device, and a profile which converts the colors of the output image device into the amount of inks according to the rule governing the use of various inks. The profile which converts the colors of the output image device into the amount of inks according to the rule governing the use of various inks is exemplified by a profile which converts the RGB data equivalent to CMY data into multi-dimensional data such as CMYKlclm data. Preparation of this profile conventionally involves color separation. This color separation is accomplished by prescribing cubic lattice points in the CMY color space and determining lattice points for the components of ink colors such that the three colors of CMY at each lattice point is converted into six colors of CMYKlclm.
The above-mentioned conventional method for determining lattice points does not meet the demand for preparing the profile capable of color conversion with high accuracy at the user level. In other words, the above-mentioned profiles or the profile after color separation are customarily prepared by the printer producer and then transferred to the user's computer when the printer driver is installed. Thus, it was impossible for the user to update them easily. Moreover, although software for preparing the ICC profile is commercially available, it is intended to prepare a profile to convert colors in the device-independent color space into colors for a specific output image device by referencing the profile to convert colors for an output image device into the ink amount conforming to the rule governing the use of various inks. Therefore, it is unable to update the profile to convert colors for an output image device into the ink amount conforming to the rule governing the use of various kinds; therefore, it was difficult to prepare a profile capable of color conversion with high accuracy.